Heavy metal ion pollution caused by agriculture and manufacturing (e.g., mining and automobile manufacturing) is a worldwide problem. Heavy metal ions include, for example, lead, arsenic, mercury, antimony and chromium (VI). The pollutants can contaminate rivers and lakes, and be a major threat to public safety, especially for drinking water.
For example, according to the World Health Organization (WHO), the health effects of long term exposure to 0.015 ppm of lead (II) include headache, irritability, abdominal pain and various symptoms related to the nervous system, and long-term exposure to chromium (VI) levels over 0.1 ppm can cause respiratory problems, kidney and liver damage. Short term and long term intake of arsenic-contaminated water can cause severe health problems, such as spontaneous pregnancy loss, respiratory complications, immunological system disorders and black foot disease.
Heavy metal removal by membrane filtration has been well demonstrated in the industry. Typically, membrane filtration approaches often involve nanofiltration or reverse osmosis, which invariably have high energy costs and can require high pressure.
Improved materials and methods for removing contaminants, including toxic heavy metal ions, from water remain desirable.